| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.dubbo.common.utils; |
| |
| import java.util.ArrayList; |
| import java.util.EmptyStackException; |
| import java.util.List; |
| |
| /** |
| * Stack. |
| */ |
| public class Stack<E> { |
| private int mSize = 0; |
| |
| private final List<E> mElements = new ArrayList<>(); |
| |
| public Stack() {} |
| |
| /** |
| * push. |
| * |
| * @param ele |
| */ |
| public void push(E ele) { |
| if (mElements.size() > mSize) { |
| mElements.set(mSize, ele); |
| } else { |
| mElements.add(ele); |
| } |
| mSize++; |
| } |
| |
| /** |
| * pop. |
| * |
| * @return the last element. |
| */ |
| public E pop() { |
| if (mSize == 0) { |
| throw new EmptyStackException(); |
| } |
| return mElements.set(--mSize, null); |
| } |
| |
| /** |
| * peek. |
| * |
| * @return the last element. |
| */ |
| public E peek() { |
| if (mSize == 0) { |
| throw new EmptyStackException(); |
| } |
| return mElements.get(mSize - 1); |
| } |
| |
| /** |
| * get. |
| * |
| * @param index index. |
| * @return element. |
| */ |
| public E get(int index) { |
| if (index >= mSize || index + mSize < 0) { |
| throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); |
| } |
| |
| return index < 0 ? mElements.get(index + mSize) : mElements.get(index); |
| } |
| |
| /** |
| * set. |
| * |
| * @param index index. |
| * @param value element. |
| * @return old element. |
| */ |
| public E set(int index, E value) { |
| if (index >= mSize || index + mSize < 0) { |
| throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); |
| } |
| |
| return mElements.set(index < 0 ? index + mSize : index, value); |
| } |
| |
| /** |
| * remove. |
| * |
| * @param index |
| * @return element |
| */ |
| public E remove(int index) { |
| if (index >= mSize || index + mSize < 0) { |
| throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + mSize); |
| } |
| |
| E ret = mElements.remove(index < 0 ? index + mSize : index); |
| mSize--; |
| return ret; |
| } |
| |
| /** |
| * get stack size. |
| * |
| * @return size. |
| */ |
| public int size() { |
| return mSize; |
| } |
| |
| /** |
| * is empty. |
| * |
| * @return empty or not. |
| */ |
| public boolean isEmpty() { |
| return mSize == 0; |
| } |
| |
| /** |
| * clear stack. |
| */ |
| public void clear() { |
| mSize = 0; |
| mElements.clear(); |
| } |
| } |